Rubber heel and sole.



O. R. WITTER.

RUBBER HEEL AND SOLE.

APPLICATION FILED FEB. 5, 1914.,

Patented Jan. 12, 1915.

l menfio r: 08207"? 727/6 rwfiorn e ya m nesse UNITED STATES PATENT OFFICE.

OSBORNE R. WITTER, 0F SWAMP SCOTT, MASSACHUSETTS.

RUBBER AND SOLE.

Application filed February 5, 1914. Serial No. 816,726.

To all wiwm' it may concern: 7

Be it known that I, OSBORNE R. Wrrrnn, a citizen of the United States, and resident of Swamps'cott, in the county of Essex and State of Massachusetts, have'invented certain new and useful Improvements in Rubber Heels and Soles, of which the following is a specification.

This invention relates to elastic treads for the heels and soles of boots and shoes, and its chief object is to provide an anti-slipping elastic tread that throughout its life shall continue to present on its bottom or tread surface a protuberant cushioning and anti-slipping portion by which the tread is given additional elasticity and greater antislipping efficiency.

, My improved tread consists of a continuous wall of rubber which surrounds and confines an insert composed of a mixture of rubber and cork fragments in proportions preferably of about four parts rubber to about one part of independent cork fragments, by weight. The wall and insert are formed separately, the insert being made normally thicker than the Wall but being subjected to compression prior to vulcanization, such compression reducing its volume so that the tread surface of the insert is held approximately flush with the tread surface of the wall. The compression of the insert may be effected by placing the assembled parts in a vulcanizing mold whose internal depth approximates closely the thickness of the wall of the tread. To insure perfect jointure of the tread wall and insert, a suitable cement may be applied to their abutting surfaces, and when the tread is vulcanized in the usual way the abutting surfaces are permanently united. When the tread is removed from the mold, after vulcanization, the edge of the insert is approximately flush with the tread surface of the surrounding wall; but the expansive force of the compressed fragments of cork contained in the insert will cause the insert always to bulge gradually, as distinguished from abruptly, beyond or below the tread surface of the surrounding wall.

The insert portion may extend through the entire thickness of the tread, or it may extend only part way, its top surface being covered by a part of the wall of unmixed rubber. Again, the tread may be made of three parts, namely, a surrounding wall of rubber, an insert composed of a mixture of Specification of Letters Patent. Patented J an. 12, 1915.

rubber and cor-k fragments, and a layer of I rubber extending across the upper surface of thewall and insert portion. I

I have shown the tread as composed of three .parts, merely to facilitate description and to avoid unnecessary duplication of draw ngs, but not with the intention of limiting the invention to a tread constructed of three parts.

On the drawings, which form a part of this specification: Figure 1 represents a bottom side view of an elastic heel-tread embodymg my invention. Fig. 2 representsa sectlon on line 2-2 of Fig. 1, showing the tread assembled, before the insert is c0m pressed or vulcanization performed. Fig. 3 1s a view similar to Fig. 2, showing the finished heel tread. Fig. at represents a bottom side view of an elastic sole-tread.

Referring to the drawings,a recess in the continuous surrounding wall of the tread is indicated at 6, this wall being made of homogeneous rubber. An insert a occupies the recess bounded by the wall I; and abuts said wall. A layer 0 of rubber extends over the top surface ofthe wall 6 and insert a. The parts 6, a and c are formed separately and assembled as shown by Fig. 1 for insertion in a vulcanizing mold the depth of which approximates the thickness of the tread wall 6. Pressure is thus brought to bear upon the insert a whereby it is reduced in thickness and its cork content is compressed. The parts I), a and 0 may be held together by a suitable cement to insure perfect unity of the parts when the tread is vulcanized, vulcanization merging their contacting surfaces. As shown by Fig. 3, after the tread is vulcanizedand is removed from the mold, the outer edge of the insert a is practically flush with the tread surface of the portion 6, but the tread surface of the insert a is forced outwardly by cubic expansion of the cork fragments embedded in the insert. Lateral expansion is resisted by the wall b, and hence the only direction of expansion possible is outwardly at the tread face. The insert a, being made of a mixture of rubber and cork fragments, as explained, affords an anti-slipping surface. By reason of the bulging insert the resistance to slipping is increased, and the tread gains greatly in liveliness, the insert acting as a cushion. I find that when the tread wears away, the acting surface of the insert a continues to bulge during the entire life of the tread, and

is not worn flat and flush with the Wearing surface of the member 6. The acting surface of the tread therefore constantly presents a bulging portion composed in part of cork, which is an anti-slipping as well as elastic material. This bulging portion, when pressed against a supporting surface, as a pavement or floor, by its effort to expand causes the surface portions of the cork fragments to cling closely to the supporting sur face.

I claim:

l. The combination with a rubber tread member provided with a tread face having a recess therein, of an insert formed ofrubber and independent compressed cork fragments vulcanized to the tread member within said recess and filling the latter and extending beyond the same in the form of a bulge, said insert being confined against lateral expansion by the wall of the recess,

whereby the exposed face of the insert maintains a permanent bulge under all conditions parts rubber and one part of independent compressed cork fragments Vulcanized to the tread member within said recess and filling the latter and extendingbeyond the same in the form of a bulge, said inser'tjbeing 'confined against lateral expansion by the wall of the recess, whereby the exposed 'face of the insert maintains a permanent bulge under all conditions of wear. In testimony whereof I signature, in presence of two witnesses,

OSBORNE R. WITTER. Witnesses;

C. F. BROWN, P. W. PEZZETTI.

have gill-ti ed myv 

